Arthroplasty is the surgical replacement of one or more bone structures of a joint with one or more prostheses. Shoulder arthroplasty often involves replacement of the glenoid fossa of the scapula with a prosthetic glenoid component. The conventional glenoid component typically provides a generally laterally or outwardly facing generally concave bearing surface against which a prosthetic humeral head (or, alternatively, the spared natural humeral head in the case of a glenoid hemi-arthroplasty) may bear during operation of the joint. The conventional glenoid component typically also includes a generally medially or inwardly projecting stem for fixing the glenoid component in a cavity constructed by suitably resecting the glenoid fossa and suitably resecting cancellous bone from the glenoid vault.
Various stem designs have been proposed for ensuring proper alignment and secure and lasting fixation of the glenoid component within the glenoid vault. However, the glenoid vault has a complex morphology. While three-dimensionally shaping a stem for compatibility with the endosteal walls of the glenoid vault can potentially significantly enhance fixation of the glenoid component, historical designs have not taken full advantage of this opportunity.
One advantageous approach is described in co-pending application Ser. No. 10/259,045, published on Apr. 1, 2004 as US2004/0064189 A1 and entitled “Concave Resurfacing Prosthesis”, the disclosure of which is incorporated herein by reference. In this approach, a glenoid component is fitted to at least partially fill a cavity formed in the glenoid vault. The component has a generally oval inverted dome shape to generally conform to the shape of the vault. However, it is recognized in the '045 Application that exact sizing of the glenoid component to the vault cavity is made difficult by the unique anatomy of each patient. To address this difficulty, the '045 Application discloses providing a series of differently sized glenoid components.
There remains a need for a glenoid component that is more nearly sized and shaped in three-dimensions to fill the cavity in the glenoid vault. There is a further need for a technique that facilitates preparation of such a component, and especially a component that has more universal applicability to the anatomy of most patients.